The spacecraft consists of a spacecraft bus, in which the
satellite control hardware and the spacecraft computers reside, and
the science payload, which point out one end of the spacecraft.
In the drawing above, the four solar panels (which are stowed,
parallel to the spacecraft, for launch) are connected at the bottom
of the spacecraft bus, and the science instruments point out the top.
On orbit, the science instruments will always be pointing away from
the sun, and the deployed solar panels will be directed toward the
sun.

More information about the various parts of the spacecraft can be
found below.